Along with Stanford Professor Baba Shiv and Wharton Business School's Cassie Mogilner, Iyengar analyzes how having all options presented at once (or "simultaneously") differs from encountering them sequentially. They found that it's a lot easier to make a decision in the first scenario. For example, when you're shopping for shoes at Zappos.com, you have the ability to compare and contrast options immediately.

It's a lot harder, and more stressful, when you encounter options sequentially over time. In that instance, you're dealing with imperfect information and the strong emotions of hope and regret. Should you wait for a better option? Or just go with it? This scenario explains why it can be especially difficult to make hiring decisions and choose a life partner, among other things. If we're not careful, focusing too much on the unknown (or un-chosen) can lead to deep dissatisfaction. The researchers write:

"This feeling of hope undermines how choosers subsequently experience their selected option, resulting in lower satisfaction and commitment levels. Sequential choosers consequently exhibit lower outcome satisfaction regardless of which option they choose, whether sequentially passed-up options remain available, and whether they have equivalent option information to simultaneous choosers. Thus, enjoying the most satisfaction from one’s choice might require being willing to give up the eternal quest for the best."

Instead of focusing on missed opportunities, it's better to make a decision and stick with it.

Iyengar and the researchers performed three experiments that validate this statement. In one, they asked 87 participants to rate several different types of chocolate in the Wharton Behavioral Lab. Some had to deal with a higher cognitive load (they were given some information to remember while testing the chocolate), and the entire group was split between either trying the chocolate sequentially or simultaneously.

They found that those who tried the chocolates sequentially — without knowledge of what was next — were less satisfied in the end, and more likely to change their minds about their top choice. "Not only are sequential choosers more likely to feel hope than simultaneous choosers, but it is this yearning for a better option that we predict reduces sequential choosers’ satisfaction with whatever option they select," says the paper. "This is because people’s satisfaction with their chosen option depends less on the objective merits of that option and more on how well that option fares against alternatives—real or imagined."